The present invention relates generally to the field of forming multi-cellular assemblies and specifically to a method for the arrangement and subsequent growth of cellular patterns ex vivo.
Growth of functional, living tissues in vitro allows the replacement of diseased or damaged tissue grown from the patient""s own cells. For example, skin and cartilage have already been grown in vitro and used for tissue replacement. These are relatively simple tissues consisting of only a few cell types anchored on a meshwork of collagen. However, tissues often comprise many different types of cells arranged in complex three-dimensional patterns. A general method of tissue engineering requires the ability to control complex tissue morphogenesis.
Tissue morphogenesis is the process by which cells grow and differentiate into functional assemblies. Organization of different cell types into a defined architecture is directed by chemical signals that control each cell""s growth, morphology, migration and differentiation. For a tissue to develop correctly, these signals must be presented at the right time and place. Creation of functional tissues in vitro requires the generation of a large number of morphogenic signals with high spatiotemporal resolution.
In order to achieve complex supercellular structures in vitro, biomolecules must be patterned with resolutions on the order of cellular dimensions. Defined patterns of cells on surfaces by patterning cell adhesion molecules to a surface and allowing cells to attach in the arrangement defined by the adhesion molecule have been demonstrated.
Biomolecular templates may be constructed by several conventional methods such as photolithography using micromachined masks, contact printing of self-assembled monolayers, or photochemical cross-linking of proteins or peptides. While these techniques are useful experimental tools, they suffer from limitations. First, the patterns generated with most of these methods are static structures that cannot be changed with time, and they are all limited to a single layer of cells. Furthermore, all but the photochemical cross-linking are limited to creating patterns of a single cell attachment protein.
Approaches that use pre-fabricated three dimensional scaffolds to direct the growth of cells have similar limitations in that they provide few chemical signals for the arrangement of cell types, with little spatial or temporal control over the presentation of chemical signals.
Various embodiments of the present invention provide both an apparatus and a method for the patterning of cells onto non-adhesive substrates and the controlled regulation of cells through the use of, e.g., photoactivated cellular morphogenic factors.
More specifically, one form of the present invention provides a method for the modification of a surface including the steps of obtaining a non-adhesive substrate and treating that substrate with a sensitizing agent and light so that the surface becomes sensitized to the attachment of biological moieties such as cells, viruses and/or fragments thereof.
Another form of the present invention is a method for immobilizing cells that includes the steps of contacting a portion of a substrate with a solution of a photoreactive sensitizing agent and exposing a portion of the substrate to a light source. Cells are then brought into contact with the surface and adhere based, e.g., on the location of light exposure of the sensitizing agent.
Yet another form of the present invention is a method for the sequential immobilization of cells including the steps of treating a portion of a non-adhesive substrate with a photoreactive sensitizing agent and exposing a portion of the substrate to a light source. One or more first cells are then contacted with the substrate, and any unimmobilized first cells are removed. The substrate is then treated again with the same or a different sensitizing agent and a different portion is exposed to the light source. One or more second cells are then contacted with the substrate.
Still another form of the present invention includes an apparatus for immobilizing cells including, a substrate that is non-adhesive to cells and a solution for treatment of the substrate. A light source irradiates a portion of the treated substrate, and a suspension of cells contacts the substrate.
Another form of the present invention is a method for the developmental control of cells including the steps of obtaining a substrate for cell attachment, contacting one or more cells with the substrate, and treating the attached cells with a light-activated cellular morphogenic factor. The light-activated cellular morphogenic factor is subsequently activated by exposing it to a light source.
An additional form of the present invention is an apparatus for the developmental control of cells. The apparatus includes a substrate for cell attachment and a light-activated cellular morphogenic factor. One or more cells that are contacted with the substrate and a light source that irradiates a portion of the substrate.
Another form of the present invention is a method for the developmental control of cells including the steps of obtaining a non-adhesive substrate and treating it with a sensitizing agent. The substrate is then exposed to a light source followed by contacting with a first biological moiety. The first biological moiety is then contacted with a light-activated cellular morphogenic factor and the cellular morphogenic factor is then activated by exposure to a second light source.
Another form of the present invention is a method for modifying the wetting properties of a substrate that is non-adhesive to cells. It includes the steps of obtaining a non-adhesive substrate and treating a portion of the substrate with a sensitizing agent and exposing a portion of the treated substrate to a light source.
1. Another form of the present invention is an apparatus that includes a non-adhesive substrate and a solution of treatment agent that contacts the non-adhesive substrate. a light source is also included that irradiates a portion of the treated non-adhesive substrate in preparation for contacting the surface with a suspension of cells.